help on tires

[1982 flareside]

My 71 F250 has a set of white spoke wheels and i was looking at the tires on the front has 15'' wheels on the front with 225/70/15 and on the back are 16'' with a pair of gumbo biasply tires. I wondering with the same wheels on the truck what tires do i need to level the truck a little better because it is riding down. I was thinking would 235/75/15 on the front and 235/85/16 on the back.

[mybros71]

Are you trying to get tires with the same overall diameter without changing the wheel diameters?

[knightfire83]

This is a helpful tool for tire sizes:

http://www.miata.net/garage/tirecalc.html

Plugging your dimensions into the calculator, the rear would have a sidewall height 1" taller than the front. This will jack up the rear of your your truck by 1". I think this is going in the wrong direction of what you want to do. What is 'riding down' exactly?

Keep in mind that these trucks do have a significant rake to them from the factory. The idea is that once the truck has a load in the bed, the truck rides at a level height.

You could always take a leaf or two out of the rear springs to level it too.... But you will have lower hauling capacity as a result of that. There is also a procedure to flip the leaf spring hangers for lowering the rear.

Check the old picture of my truck when it was a 2wd f250. The tires were all 16" and the same size. The rake is very noticeable.

[1982 flareside]

I mean to make the truck level like the front will be taller because 15'' wheels.

[ToughOldFord]

These trucks were built with the rear higher, so you could put a load in it and be level. If you're determined to make it level it'd probably make more sense to lower the rear, (I can't believe I'm saying this), to match the front rather than raising the front via oversized tires. Note also that the front coil springs in old Fords tend to sag and lower the front as a result. If this is the case you could get that front end back up with a set of new springs.

And is there a reason you're running 15" on the front? You might want to consider matching your front rims to your rear.

And to second Knightfire's question, what do you mean by 'riding down'? Do you mean sagging? Any pics of your truck so we can see how it's sitting?

[ToughOldFord]

Okay, I just found your pics in Image Shack, and making mental adjustments for the front flat tire it looks like it's sitting like it should so maybe some more input would be handy here.

BTW, a 15" wheel is smaller than a 16" wheel so it is not going to raise your front end by running the 15", but rim size isn't necessarily relative to the overall height of a tire/wheel assembly.

[1982 flareside]

I found 2 16'' wheels like on the very back of shed, they are the same style wheels as on the back so it will sit up a little higher. The bad is the only tires we have is a pair of old gumbo mudders.

[1982 flareside]

I found 2 16'' wheels like on the very back of shed, they are the same style wheels as on the back so it will sit up a little higher. The bad is the only tires we have is a pair of old gumbo mudders.